The automaker said Monday it will start construction this year on a 450,000-square-foot paint shop, a new stamping press and other improvements at the Fairfax Assembly Plant.

"That's huge! I wasn't expecting that," said worker Clarence Brown.

GM CEO Dan Akerson says the investment is a "vote of confidence" in the Fairfax plant, where the company has produced more than 12 million vehicles since 1945. GM announced earlier this month it planned to invest $1.5 billion in its North American facilities in 2013.

"When we're done, this will be one of the jewels in the crown of the GM universe," said Akerson.

"Right now, it costs between $50 and $60 to paint a car. This plant will cut that cost by about 50 percent," Akerson said.

Employees said the investment suggests General Motors has a long-term plan for the Fairfax plant.

"It's kind of a relief. Now we know. People have been walking on eggshells," said employee Darren Walker.

Some 3,900 employees work at the Fairfax plant, where the company produces the Buick LaCrosse and Chevrolet Malibu. The project is not expected to lead to any additional jobs at the plant, although suppliers may see more work.